test

README.md

@@ -99,10 +99,11 @@ To use a different camera:
   automatically after a successful print. (If the program is restarted
   mid-cycle, photos here are counted so no progress is lost.)
 - `contact_sheets/` — every printed sheet, kept as a backup in case of
-  printer trouble. Sheets are full US-letter pages at 300 DPI, so they
-  also print at the right size from any other app. Delete them manually
-  now and then, or set `delete_contact_sheets = true` in the config to
-  remove each one right after it prints.
+  printer trouble. Each sheet has two files: a `.jpg` (handy for viewing)
+  and a `.pdf` twin — the PDF is a full US-letter page at exactly 300 DPI
+  and is what actually gets sent to the printer. Delete them manually now
+  and then, or set `delete_contact_sheets = true` in the config to remove
+  each one right after it prints.
 
 ## If printing fails
 
@@ -111,9 +112,12 @@ The booth doesn't lose anything: the contact sheet is saved in
 sheet by hand with:
 
 ```bash
-lp -o media=letter -o fit-to-page contact_sheets/sheet_XXXX.jpg
+lp -o media=letter -o fit-to-page contact_sheets/sheet_XXXX.pdf
 ```
 
+(Print the `.pdf`, not the `.jpg` — the PDF's page size is exact, so the
+printer can't stretch the photos.)
+
 Common causes: printer off or unplugged (`lpstat -p` says "disabled" —
 re-enable with `cupsenable PRINTER_NAME`), or no default printer set.
 

config.toml

@@ -63,6 +63,6 @@ printer = "HP-LaserJet-P2055d"
 # Set to false while testing: contact sheets are still composed and saved,
 # but nothing is sent to the printer (and photos are still cleaned up).
 enabled = true
-# true = delete each contact sheet immediately after it prints.
+# true = delete each contact sheet (JPEG + PDF) immediately after it prints.
 # false = keep them in contact_sheets/ in case something goes wrong.
 delete_contact_sheets = false

contact_sheet.py

@@ -17,13 +17,17 @@ that maximizes each printed photo's area on a fixed 8.5x11 letter sheet
                         a strip has few photos and a wide page fills better
                         (e.g. 1 photo per shoot, or one big photo).
 
-The date is printed only inside the footer. Sheets are saved with 300-DPI
-metadata so their physical print size is well-defined (a full letter page)
-for CUPS or any other program they are printed from.
+The date is printed only inside the footer.
+
+Each sheet is saved twice: a JPEG (300-DPI metadata, handy for viewing or
+reprinting from other apps) and a PDF twin whose page geometry is exactly a
+300-DPI letter page. `print_sheet` sends the PDF, so the print pipeline
+rasterizes exactly what was composed - no image-DPI guessing, no warping.
 """
 
 import subprocess
 from datetime import datetime
+from pathlib import Path
 
 from PIL import Image, ImageDraw, ImageFont
 
@@ -234,24 +238,34 @@ def build_sheet(photo_paths, out_path, footer_cfg=None,
     # Stamp 300 DPI into the file: without it the sheet has no defined
     # physical size and the print pipeline has to guess (and may stretch).
     sheet.save(out_path, quality=95, dpi=(300, 300))
+
+    # PDF twin: page size is exactly a 300-DPI letter page, so printing it
+    # reproduces the composed geometry 1:1 (PIL maps pixels at `resolution`
+    # DPI onto the PDF page).
+    sheet.save(Path(out_path).with_suffix(".pdf"), "PDF", resolution=300.0)
     return out_path
 
 
 def print_sheet(path, printer=""):
     """Send the sheet to the printer via lp. Returns (ok, message).
 
-    fit-to-page scales uniformly, so the sheet's aspect ratio is preserved.
-    Passing the sheet's orientation explicitly keeps a landscape sheet from
-    being rotated or squeezed by driver defaults.
+    Prefers the sheet's PDF twin (exact page geometry) when it exists, and
+    falls back to the image itself. fit-to-page scales uniformly, so the
+    sheet's aspect ratio is preserved. For plain images we also pass the
+    orientation explicitly so a landscape sheet is not rotated or squeezed
+    by driver defaults; a PDF carries its orientation in its page size.
     """
-    with Image.open(path) as im:
-        sheet_w, sheet_h = im.size
-    orientation = "landscape" if sheet_w > sheet_h else "portrait"
-    cmd = ["lp", "-o", "media=letter", "-o", "fit-to-page",
-           "-o", orientation]
+    path = Path(path)
+    job = path.with_suffix(".pdf")
+    job = job if job.exists() else path
+    cmd = ["lp", "-o", "media=letter", "-o", "fit-to-page"]
+    if job.suffix.lower() != ".pdf":
+        with Image.open(job) as im:
+            sheet_w, sheet_h = im.size
+        cmd += ["-o", "landscape" if sheet_w > sheet_h else "portrait"]
     if printer:
         cmd += ["-d", printer]
-    cmd.append(str(path))
+    cmd.append(str(job))
     try:
         result = subprocess.run(cmd, capture_output=True, text=True, timeout=30)
     except (OSError, subprocess.TimeoutExpired) as e:

photobooth.py

@@ -246,6 +246,7 @@ class Booth:
             self.falling.reload()
             if printing["delete_contact_sheets"]:
                 sheet_path.unlink()
+                sheet_path.with_suffix(".pdf").unlink(missing_ok=True)
             self.shoots_done = 0
             self.set_notice("Sent to printer!")
         else:

test_contact_sheet.py

@@ -12,6 +12,7 @@ quadrant that lands in the cell's top-left corner tells us whether the
 applied transpose is CCW (correct) or CW (the bug we fixed).
 """
 
+import re
 import sys
 import tempfile
 from pathlib import Path
@@ -129,6 +130,18 @@ def check_layout_combos():
                 sheet = opened.convert("RGB")
             assert sheet.size == (page_w, page_h)
 
+            # PDF twin: page must be exactly the sheet's pixel size at
+            # 300 DPI, in points (1/72in) - that is what the printer sees.
+            pdf = out.with_suffix(".pdf")
+            assert pdf.exists(), "PDF twin not written"
+            m = re.search(rb"/MediaBox\s*\[\s*0[ ,]+0[ ,]+([\d.]+)[ ,]+([\d.]+)\s*\]",
+                          pdf.read_bytes())
+            assert m, "PDF MediaBox missing"
+            pw, ph = float(m.group(1)), float(m.group(2))
+            want_w, want_h = page_w * 72 / 300, page_h * 72 / 300
+            assert abs(pw - want_w) < 1 and abs(ph - want_h) < 1, (
+                f"PDF page {pw}x{ph}pt != ~{want_w}x{want_h}pt")
+
             for i, r in enumerate(layout["photo_rects"]):
                 got = sheet.getpixel(rect_center(r))
                 exp = colors[i]
@@ -231,12 +244,53 @@ def check_falling_photos_rotation_halved():
     print(f"  ROT=±{fp.ROT_MAX}  SPIN=±{fp.SPIN_MAX}  OK")
 
 
+def check_print_sheet_prefers_pdf():
+    print("== print_sheet job selection ==")
+    calls = []
+
+    class FakeResult:
+        returncode = 0
+        stdout = "ok"
+        stderr = ""
+
+    def fake_run(*a, **k):
+        calls.append(list(a[0]))
+        return FakeResult()
+
+    orig = cs.subprocess.run
+    cs.subprocess.run = fake_run
+    try:
+        with tempfile.TemporaryDirectory() as d:
+            jpg = Path(d) / "s.jpg"
+            Image.new("RGB", (3300, 2550), (10, 20, 30)).save(jpg, dpi=(300, 300))
+
+            # No PDF yet: prints the JPEG, with explicit orientation.
+            ok, _ = cs.print_sheet(jpg, "SomePrinter")
+            assert ok
+            argv = calls.pop()
+            assert argv[-1].endswith("s.jpg"), argv
+            assert "landscape" in argv, argv
+            assert "-d" in argv and "SomePrinter" in argv, argv
+
+            # PDF twin exists: it wins, and no orientation flag is needed.
+            jpg.with_suffix(".pdf").write_bytes(b"%PDF-1.4 fake")
+            ok, _ = cs.print_sheet(jpg, "SomePrinter")
+            assert ok
+            argv = calls.pop()
+            assert argv[-1].endswith("s.pdf"), argv
+            assert "landscape" not in argv and "portrait" not in argv, argv
+    finally:
+        cs.subprocess.run = orig
+    print("  JPEG fallback gets orientation; PDF twin preferred  OK")
+
+
 def main():
     check_layout_combos()
     check_rotation_mode_expectations()
     check_rotation_direction()
     check_default_config_shape()
     check_falling_photos_rotation_halved()
+    check_print_sheet_prefers_pdf()
     print("\nAll tests passed.")